Process for the preparation of a diester of adipic acid

Abstract

Process for preparing adipic acid or esters thereof by:- (1) reacting 1,3-butadiene with CO and water or an alcohol with formation of pentenoic acid or esters thereof in the presence of a first carbonylation catalyst comprising a Pd compound and a polydentate ligand containing P, As or Sb, (2) isolating pentenoic acid or esters thereof from the reaction mixture, and (3) reacting the isolated pentenoic acid or esters with CO and water or an alcohol in the presence of a second carbonylation catalyst. )

We claim: 
     
       1. A process for the preparation of a compound of formula I ##STR9## wherein each Z represents a hydrogen atom or a hydrocarbon group, which process comprises: (a) contacting 1,3-butadiene with carbon monoxide and a compound of formula II   ZOH                                                        (II)         in which Z represents a hydrogen atom or a hydrocarbon group, in the presence of a first carbonylation catalyst prepared by combining a palladium compound and a polydentate ligand having formula III ##STR10##   wherein each M represents an atom of Group VA of the Periodic Table of the Elements having an atom number in the range of from 15 to 51, R represents a divalent organic bridging group having in the range of from 2 to about 6 carbon atoms in the bridge, none of these carbon atoms carrying substituents that may cause steric hindrance, and R 1 , R 2 , R 3  and R 4  each represent hydrocarbon group, thereby forming a compound of formula IV ##STR11##   in which Z represents a hydrogen atom or a hydrocarbon group; (b) isolating the compound of formula IV from the reaction mixture obtained in (a), and   (c) reacting the compound isolated in (b) with carbon monoxide and a compound of formula II in the presence of a second carbonylation catalyst.   
     
     
       2. The process of claim 1 wherein each M in the general formula III represents a phosphorus atom. 
     
     
       3. The process of claim 1 wherein a protonic acid having a pK a  greater than about 3, measured at 18° C. in aqueous solution, is incorporated in the first carbonylation catalyst. 
     
     
       4. The process of claim 3 wherein protonic acid having a pK a  greater than about 3 is a sterically hindered carboxylic acid. 
     
     
       5. The process of claim 4 wherein the sterically hindered carboxylic acid is a sterically hindered benzoic acid. 
     
     
       6. The process of claim 3 wherein a molar ratio protonic acid having a pK a  greater than about 3 to polydentate ligand having formula III in the range of from 1.0 to 10 is used in (a). 
     
     
       7. The process of claim 1 wherein (a) is carried out with a ratio gram-atom of palladium per mol of 1,3-butadiene, in the range of from about 10 -5  to about 10 -1 , a ratio mol of polydentate ligand per gram-atom of palladium in the range of from about 1 to about 10 and a molar ratio compound of formula II to 1,3-butadiene in the range of from about 0.1 to about 10. 
     
     
       8. The process of claim 7 wherein said process is carried out at a temperature in the range of from about 50° C. to 200° C. and a partial pressure of carbon monoxide in the range of from about 25 to about 100 bar. 
     
     
       9. The process of claim 1 wherein the second carbonylation catalyst is prepared by combining: (a) palladium and/or a palladium compound,   (b) an acid having a pK a  below about 2.0, measured at 18° C. in aqueous solution, except hydrohalogenic and carboxylic acids, and   (c) a polydentate ligand having formula III in which R represents a divalent organic bridging group having in the range of from 3 to 6 carbon atoms in the bridge.   
     
     
       10. The process of claim 9 wherein a molar ratio of acid having a pK a  below about 2.0 to polydentate ligand greater than about 0.5 is used. 
     
     
       11. The process of claim 1 wherein the polydentate ligand present in (a) has in the range of from about 3 to about 6 carbon atoms in the bridge of group R. 
     
     
       12. The process of claim 1 wherein the bridge in group R in formula III exclusively consists of carbon atoms. 
     
     
       13. The process of claim 1 wherein R 1 , R 2 , R 3  and R 4  in formula III each represent an aryl group having in the range of from 6 to about 14 carbon atoms. 
     
     
       14. The process of claim 13 wherein R 1 , R 2 , R 3  and R 4  each represent a phenyl group. 
     
     
       15. The process of claim 12 wherein the polydentate ligand of formula III is 1,3-di(diphenylphosphino)propane or 1,4-di(diphenylphosphino)butane. 
     
     
       16. The process of claim 1 wherein said palladium compound is palladium acetate. 
     
     
       17. The process of claim 9 wherein said palladium compound is palladium acetate. 
     
     
       18. The process of claim 9 wherein the acid having a pK a  below about 2.0 is an acid (a) that can be formed by interaction of a Lewis acid with a Broensted acid or (b) having formula VII ##STR12## in which X represents a sulfur or a chlorine atom and, if X represents a chlorine atom, R 9  represents an oxygen atom and, if X represents a sulfur atom, R 9  represents an OH group or a hydrocarbon group. 
     
     
       19. The process of claim 18 wherein the hydrocarbon group represented by R 9  is selected from the group consisting of an alkyl, aryl, aralkyl or alkaryl group having in the range of from 1 to about 30 carbon atoms. 
     
     
       20. The process of claim 19 wherein the acid is selected from the group consisting of p-toluenesulfonic acid and trifluoromethanesulfonic acid. 
     
     
       21. The process of claim 1 wherein (c) is carried out with a ratio gram-atom of palladium per mol of compound of formula IV in the range of from about 10 -5  to abut 10 -1 , a ratio mol of polydentate ligand per gram-atom of palladium in the range of from about 1 to about 10 and a molar ratio compound of formula II to compound of the general formula IV in the range of from about 10:1 to about 1:1. 
     
     
       22. The process of claim 21 wherein said process is carried out at a temperature in the range of from about 50° C. to about 200° C. and a partial pressure of carbon monoxide in the range of from about 25 to about 100 bar. 
     
     
       23. The process of claim 1 wherein the reaction mixture obtained in (c) is separated by means of distillation into a distillate fraction containing the compound of the general formula I and a residual fraction containing the second carbonylation catalyst, which catalyst is recycled to (c) for re-use. 
     
     
       24. The process of claim 1 wherein the second carbonylation catalyst is prepared by combining a cobalt carbonyl and a tertiary amine. 
     
     
       25. The process of claim 24 wherein the tertiary amine is N-heterocyclic. 
     
     
       26. The process of claim 21 wherein the N-heterocyclic tertiary amine is selected from the group consisting of pyridine, an alkyl- or alkoxy-substituted pyridine in which the alkyl or alkoxy groups have in the range of from 1 to about 5 carbon atoms, and a cycloalkyl-, cycloalkyloxy-, aryl- or aryloxy-substituted pyridine in which the cycloalkyl, cycloalkoxy, aryl or aryloxy groups have in the range of from 6 to about 14 carbon atoms. 
     
     
       27. The process of claim 26 wherein the tertiary amine is selected from the group consisting of 3,4-dimethylpyridine and 4-phenoxypyridine. 
     
     
       28. The process of claim 24 wherein(c) is carried out with a molar ratio cobalt carbonyl to compound of formula IV in the range of from about 1:50 to about 1:1000, a molar ratio cobalt carbonyl to tertiary amine in the range of from about 1:1 to about 1:100 and a molar ratio compound of formula III to compound of formula IV in the range of from about 10:1 to 1:1. 
     
     
       29. The process of claim 28 wherein said process is carried out at a temperature in the range of from about 120° C. to about 200° C. and a pressure in the range of from about 25 to about 100 bar. 
     
     
       30. The process of claim 1 wherein Z in the general formula I represents an alkyl group having in the range of from 1 to about 5 carbon atoms. 
     
     
       31. The process of claim 30 wherein Z represents a methyl or an ethyl group. 
     
     
       32. The process of claim 1 wherein (b) is carried out by means of distillation into a distillate fraction containing the compound of formula IV and a residual fraction containing the first carbonylation catalyst which catalyst is recycled to (a) for re-use.